Sharpening Part 22 – The Double-Bevel Blues

The fool doth think he is wise, but the wise man knows himself to be a fool.

William Shakespeare, As You Like It

It is well with me only when I have a chisel in my hand – Michelangelo Buonarroti 1475-1564

In the previous post in this series on sharpening Japanese tools, we looked at philosophical points such as making tools a long-term investment, as well as the upsides, downsides and causes of the bulging bevel. In this post, I would like to touch on a subject that will make thoughtful people think and befuddled folks lucid: The Double Bevel.

The Double-Bevel

Some people advocate creating double-bevels (primary and secondary) bevels, or what is sometimes called “micro-bevels” on plane and chisel blades. Multiple bevels have three useful applications in my opinion:

The first useful application is to repair a tool’s blade in the field when there is not enough time to do a proper sharpening job. If a blade dulls or chips in the course of a job, we can quickly add a secondary bevel at a steeper angle to the blade’s primary bevel in a few seconds and get right back to work, but there will be a price to pay later over many sharpening sessions to restore the proper bevel, so it is only a temporary, not a long-term solution;

The second application is to quickly adjust a plane blade’s angle to reduce tearout immediately when proper sharpening is not possible. Once again, a lot of remedial sharpening becomes necessary afterwards. This application is usually restricted to the primary bevel, but we will look at a more esoteric and risky application below.

The third application is to efficiently restore a blade’s bevel to the correct angle in the case where pixies or our inattention has made the blade angle too shallow.

Case 3 above often goes like this: A blade that cuts well suddenly starts dulling quickly, maybe even chipping. Whiskey tango foxtrot!?! When this happens, our Beloved Customers, being of exceptionally high intelligence, use the bevel angle gauge described in Part 11 of this series to check the bevel angle. They may discover the bevel angle has become too shallow for the wood it is being asked to cut.

We could increase the bevel angle by welding metal to the bevel and regrinding it, but such barbaric behavior would ruin the blade, so the most expedient way to correct the bevel is to add a steeper secondary bevel at the desired angle. We can grind this new bevel by hand, or use a honing jig like the Lie-Nielson widget. I find I can apply more downward pressure using this jig to get the job done sooner and more precisely.

Honing jigs are undeniably useful, but they often become an impediment to learning professional sharpening skills, and they are more time-consuming to use than freehand sharpening. Jigs can certainly make the sneaky snake of multiple bevels workable, but please don’t ignore the inescapable fact that if one uses a jig properly, over multiple sharpening sessions the result will be… let me think about it…. wait a second while I make a little sketch here…. oh yea, a flat bevel. Hmmm….

Hey, I’ve got an idea. When performing routine sharpening (not the 3 cases listed above), instead of taking shortcuts and adding micro-bevels which turn into secondary bevels and maybe even bulging bevels, why not start with a flat bevel and keep it flat? And then just maybe we could take advantage of the natural indexing properties of that flat bevel to sharpen freehand and save a lot of time NOT polishing skinny secondary bevels or fat bulging bevels? You know what, it just might work!

A honing jig is very helpful for making big angle corrections. I own several, but the Lie-Nielson model is my favorite: I use it every third blue moon. If you decide to use one, however, reserve it for emergency or drastic measures. Don’t let it become training wheels, kiddies.

The Nano-bevel

In this and previous posts we discussed bulging bevels, which are convex bevels on plane or chisel blades; secondary bevels and double bevels, which are additional bevels; and micro-bevels, which are a tiny secondary bevel. But there is another type of secondary bevel a clever Beloved Customer called a “nano-bevel.” I like this term and so will use it, but I caution you that, like all secondary bevels, you should employ this bevel judiciously.

We will go into freehand sharpening techniques in greater detail in future posts, but to avoid confusion when discussing the nano-bevel, we need to touch on some of those techniques now.

You may have noticed that, when sharpening freehand on every stone but the finish stone, most, but not all people do a better job by applying downward pressure on the blade only on either the push stroke away from their body or the pull stroke back towards their body, but not in both directions. This is because placing downward pressure in both directions tends to make the blade rock resulting in a less-than-flat bevel, or Saints preserve us, the demonic bulging bevel. As you can imagine, if this rocking motion gets out of hand on the rougher stones the bevel angle can get out of control quickly.

However, on the finish stone, it is most efficient to apply light downward pressure in both directions. The advantage is that a teeny tiny bit of unintentional rocking helps to ensure the last few microns of the blade’s cutting edge are thoroughly polished. And because the abrasive power of a finish stone is so small, there is no danger the bevel will become rounded, at least if you don’t get carried away. From the wood-shaving’s eye view, this creates a tiny bevel at the last few microns of the cutting edge. This is one example of a “nano-bevel.” Stropping produces the same result on a larger scale. There is also another type of nano-bevel for emergency use.

When using a finish plane on wood with twisty grain you have no doubt experienced frustrating tearout. The usual litany of solutions is to reduce the blade’s projection for finer depth of cut, skew the plane, oil and adjust the chipbreaker, resharpen the blade, adjust the plane’s mouth, or even slightly dampen the wood with a planing fluid such as water, whiskey, or unicorn wee wee. All these methods can help.

On the subject of planing fluid, water works well but dries slowly and can have problematic secondary effects. And unicorn products are dreadfully expensive nowadays, even on Amazon, so I prefer a smooth, inexpensive, industrial-grade busthead. Please ask Ken Hatch for a demonstration and recommendations for a good planing fluid next time he invites you over to his house for his world-famous tacos.

Please note that I don’t drink any planing fluid other than water. Of course unicorn wee wee is more addictive than OxyContin and drives mortals quite mad. And alcohol is yeast pee pee and deadly, but I prefer whiskey for a number of reasons. First, whiskey has a good water/alcohol ratio that wets the wood about the right amount of time and then evaporates cleanly. Too wet and it penetrates too deeply. Too dry and it evaporates too quickly. Isopropyl alcohol works fine too but it is considered a pharmaceutical in Japan and so is very expensive. As with other alcohol products not intended for internal consumption, it contains poisons added at the demand of greedy governments for the sole purpose of maximizing tax revenues. I don’t need those poisons touching my tools or my skin. Whiskey doesn’t contain poisons (other than alcohol, of course), it’s cheaper and smells better.

Another classic solution to reduce tearout of course is to use a plane with a steeper blade bedding angle, but what to do if you don’t have a high-angle plane handy? A traditional, jobsite-expedient solution used by Japanese woodworkers is to create a nano-bevel on the ura side of the blade. This is accomplished during sharpening while polishing the ura on the finishing stone by lifting the head of the blade just a itsy bitsy teeny weeny nat’s nosehair thickness during the final stroke, pulling the blade towards you, of course, creating a “nano-bevel” on the last few microns of the cutting edge at the ura, effectively changing the approach angle of the blade.

Be forewarned that this is only for emergency use, and that if you are careless, or use it too often, the nano-bevel will become a microbevel, your blade will be damaged, efficient sharpening will become impossible, the chipbreaker will cease to function, and the gods of handsaws may curse you so all your hair will fall out and your dog will barf whenever it sees you! Or is it your dog’s hair will fall out and you will barf? I forget.

Now where did I set down that jar of planing fluid….?

Conclusion

A wise man will seek to avoid shortcuts that save a bit of time short-term only to waste more of his time and money long-term. If you simply make the effort to train yourself in basic sharpening skills, pay attention, and keep the bevel flat, time, steel, and stone-wasting monkeyshines such as double bevels will be unnecessary.

We have talked about the cutting edge’s proper shape. Beginning with the next post in this series, we will examine how to use sharpening stones to make it that way.

YMHOS

Well Dude, I’m done sharpening using my most excellent honing jig for now and am off to the beach on my chick magnet! Don’t wait up, Mom.

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16 thoughts on “Sharpening Part 22 – The Double-Bevel Blues”

Heard much about ‘jointing the edge’? Harrelson Stanley seems to be the first or one of the first examples I can find of this, not sure where it originated. Supposedly to get rid of that very very last bit of microscopic bur by extremely gently running the blade edge across your finishing stone once or twice as lightly as possible on the blades edge.

I like my honing crutch. Nature’s solutions to maintain constant assurances of flat over a grinding marathon have been a bit brutalized (traumatised) over the years. Besides, the last time I did freehand, with a Japanese chisel, the pads of my fingers were shredded and the stone lubricated with blood; more so than I realized.

Regarding multiple secondary, or primary–maybe–bevels, you couldn’t be more accurate. I will take care of that Stanley antique with my crutch.

I was working on some chisels tonight and I did the Nano bevel thing…. I kind of measured it and it look like 1 fifth of a mm…. So really really fine!!
Thank you again for the great right up. I need to go back to part 20 again and reread that!!

Remember, it’s only a tiny thing and temporary only. I don’t want people to get the mistaken idea that I am advocating the excellent (I write this with all sincerity) Mr. Charlesworth’s “Ruler Trick.” It is not a good long-term solution for Japanese blades, anymore than the method we are discussing is.

Lift the blade only a nat’s eyelash, and then remove the nano bevel entirely during the next sharpening session. If tearout is a constant problem, and the other solutions I mentioned, even unicorn wee wee, don’t solve it, then you should buy or make a high-angle plane, or try a card scraper. Most box-stock Japanese planes are not high-angle, but they are routinely made or ordered.

At one fifth of a mm you can be sure that it would disappear after a few stroke on the 1K stone!! I don’t do it all the time and not on all tools! I have to chop some joints in white ash and I want the edge to be a little stronger!!

If you are chopping, then that means a chisel, not a plane, which is a horse of a different color, as “The Wiz” said it. In which case, a nano-bevel on the bevel side makes perfect sense. And as I mentioned in the article, sometimes a bulging bevel on a chisel used to chop deep mortises is actually preferred because it kicks chips out of the mortise quicker. 2 cents.

Everyone does everything a little differently day to day and job to job. Methods and tools change, and most of those changes work just fine. For instance, when I was making a living with my hands and tools, diamond plates were not an option. Now their quality, performance and durability have dramatically improved while cost has decreased. They are almost indispensable. I would be a hide-bound fool to ignore that fact just because of tradition, or because the people who taught me back when dinosaurs roamed the earth did not use them. Things have changed and so have my methods.
The techniques I present in this blog are not the only way to get the job done. Japan is a strange disjointed country in many ways with a strange history. The techniques I learned in Tokyo decades ago are different in many small ways from what someone trained in Osaka may think are best. But I do know how to get good performance from and maximize the longevity of tools. This blog exists because friends and customers asked me to help them understand how to do this with confidence. I try hard to keep my motives pure and clear as glass. You be the judge.

And you do an exceptional job at it and all this info should be made into a book, like a real book paper hard cover glossy pictures, something that can be pass down to future generations!! I would buy it even if it was $100(Canadian though 😁)
I do what I do for a living, or try to make a living out of it, 2 days a week on the job site as a carpenter and the rest in my shop making furnitures(and all kind of stuff using wood!! ) on the job site I work and worked with guys that think there is only one way to do things and usually it is there way or the highway….
like people say there is more than one way to skin a cat!!
Tell me when the book is ready I’ll be the first one to send you money!!

Well you would be surprise I think!! There is a few group on Facebook that are all about Japanese woodworking and tools, also there is a few Japanese craftsmen that have started schools in English, and there is a few schools in the USA that do works shops… and all that is in English and look like that as sprung a large interest in the Japanese tools and techniques!!
But may I’m wrong and no body get rich with books!!

I always put a “micro” bevel on the back of my block plane blades. I put a 30 degree angle on the bevel and a small 5 degree bevel on the back. This way the angle of attack stays 42 degrees (the bed of the block plane is set at 12 degrees) while I effectively have a 35 degree bevel on the blade for extra strength and durability and 7 degrees of clearance.